The dG9 antibody clone reacts with human perforin (pore-forming protein, pfp). Perforin is one of the cytolytic mediators present in the cytoplasmic granules of cytotoxic T lymphocytes (CTL) and natural killer cells (NK). Perforin is involved in the killing function by CTLs and NKs and has an important role in the immune response against tumors and virus infections.